1. Field of the Invention:
This invention relates to tractor trailer beds, truck beds and the like, and more particularly to a vehicle having a horizontal transport platform or bed with steps mounted within the horizontal platform.
2. Related Prior Art:
Horizontal transport platforms on vehicles are well-known. Examples of these include city trucks, the trailer portion of semi-trucks and various forms of tow behind trailers. In each of these cases, platform height is determined by wheel diameter. In some instances, wheel diameter may be on the order of four feet, in which instance the platform height exceeds four feet. These high platforms make it difficult to load and unload materials from the platform. In addition, as platform height increases, there is a danger of cars sliding under the rear of the platform and possibly decapitating the operator of the vehicle. Various solutions to these problems have been advanced in the prior art.
A first category of solutions involves external steps fixed permanently to the rear of the platform. U.S. Pat. No. 4,266,817 issued on May 12, 1981, to James L. Mason and entitled Rear Step Bumper; U.S. Pat. No. 2,660,454 issued on Nov. 24, 1953, to Counerilth and entitled Combined Rear Trailer Bumper and Step; U.S. Pat. No. 3,708,198 issued on Jan. 2, 1973, to Coons and entitled Convertible Trailer Porch and Camper; and Design Pat. No. 267,166 issued on Dec. 7, 1982, to Sambucetti et al and entitled Semi-Trailer all disclose external fixed steps. The steps are rigidly attached to the rear portion of a horizontal platform on, respectively, a pick-up truck bumper, a city truck, a trailer porch, and a trailer. Each of these patents disclose a means for providing access to an elevated transport platform, but require that the overall length of the vehicle be increased in order to provide this access.
A second category of prior art patents solve the problem of platform access without adding length to a transport platform. They do this by adding a retractable set of steps to the transport platform. The steps and the retraction thereof, however, are a complex and expensive addition to the platform. Examples of this teaching are U.S. Pat. No. 3,858,905 issued on Jan. 7, 1975, to Peebles and entitled Demountable Safety Ladder With Handrail; U.S. Pat. No. 2,779,525 issued on Jan. 29, 1957, to Vogel and entitled Truck Extension Ladder; U.S. Pat. No. 2,544,799 issued on Mar. 13, 1951, to McCann entitled Yielding Vehicle Step; and U.S. Pat. No. 7,591 issued on Aug. 27, 1850, to Burdett and entitled Carriage Step. Each of these patents disclose retractable steps in the rear portion of, respectively, a house trailer, a city delivery vehicle and a carriage. The problem with these steps is that they are expensive and difficult to manufacture, require labor each time they are used to retract and deploy them, and the steps can be damaged due to their flexible design.
There remains a need for providing access to transport platforms without increasing the length of the platform or the expense, complexity and labor associated with retractable steps.